Stoker



May 5, 1936.

s. e. BUSKARD sT KER' Filed Oct 10, 1952 4 Sheets-Sheet 1 INVENTOR flan/0E1 629061 0920 ATTORNEY May 5, 1936. s. s. BUSKARD STOKER Filed Oct. 10, 1932 4 Sheets-Sheet 2 vhu w w w L l l /IIII/l! IIIIIIIIIIlII1I MW n %N l 3% R M Qu h, i I 1% May 5, 1936. s. G. BUSKARD 2,039,389

STOKER Filed Oct. 10, 1932 4-Sheets$heet 3 Sign,

May 1936.- s. G. BUSKARD 2,039,389

STOKER Filed Oct. 10, 1932 4 Sheets-Sheet 4 llllllllll l I INVENTOR 62w? 6'. Bus/r400 BY 9o" 8 1 ATTO R N EY Patented May 5, 1936 UNITED STATES PATENT OFFICE STOKER Samuel G. Buskard, Richmond Hill, N. Y. Application October 10, 1932, Serial No. 637,093

4 Claims. (o1. 110-45) This invention relates to a stoker of the underfed type whereby fuel such as coal for the furnace is fed from a suitable supply upwardly into a fire pot of rotary type whereby the coal is fed upwardly towards the grate of the furnace and into the bed of burning fuel, the apparatus being preferably provided with means for automatically carrying away and disposing of the ashes, the coal dust, etc.

One of the objects of the present invention is to provide a rotatable fire pot which is supported for a step by step rotary motion and whereby the incoming supply of fuel in the pot is somewhat agitated and distributed for efiicient application to the burning bed of fuel.

Another object of the invention is to provide a screw conveyor for leading the supply of fuel underneath and upwardly into the fire pot, the shaft of which conveyor acts upon means for imparting the step by step rotary motion to the fire pot.

Another object of the invention is to provide means acted upon by the shaft of the screw conveyor for the purpose of automatically shutting off the power, in the event that clogging or a sluggish action of the feed of the fuel by the conveyor occurs.

Another object of the invention is to provide the fire pot with air distributing perforations-for admitting into the pot a supply of air from an annular chamber surrounding the pot, which supply of air is preferably obtained by means of a blower operated by the same source of power as operates the screw conveyor, so that by the air admitted in jets into the pot, the fuel therein is rendered more serviceable for combustion and whereby combustion of the fuel in the fuel bed above the stoker is facilitated.

A further object of the invention is to provide means for automatically carrying away the ashes which are discharged from the burning fuel bed, such means preferably involving the use of a second screw conveyor located iii a trough below the fire pot.

Still another object of the invention is to provide means which are adapted from time to time to discharge dust or the like which may be eliminated through the perforations in the fire pot, such means preferably discharging the accumulatlon so as to be carried away by the secnd screw conveyor.

Other objects of the invention areto provide an extremely efficient, practical and economical stoker," adapted for use in connection with various types of coal burning furnaces used for various purposes.

These being among the objects of the present invention, the same consists of certain features of construction and combinations of parts to be hereinafter described and then claimed with reference to the accompanying drawings illustratlng one embodiment of the invention and wherein Fig. 1 is a plan of the stoker, including the power means and other accessories;

Fig. 2 is a vertical longitudinal section, partly in elevation and parts broken, the section being taken in the vertical plane of the screw conveyers and the fire pot; I

Fig. 3 is a detail horizontal section on the line 33, Fig. 2;

Fig. 4 is an end elevation, partly broken away, of the apparatus as viewed from the left hand end of Figs. 1 and 2;

Fig. 5 is an elevation, partly in section, of parts of the apparatus directly adjoining the fire pot and illustrating means for imparting a. step by step rotary motion thereto;

Fig. 6 is a sectional elevation of the fire pot and concomitant parts;

Fig. 7 is a detail section of the fire pot to illustrate a possible modification;

Fig. 8 is. a detail sectional elevation to illustrate the means whereby the source of power is automatically cut off in the event of clogging of the apparatus; and

Fig. 9 is a section on the line 9--9, Fig. 8.

Referring to Figs. 1 and 4, the stoking apparatus is preferably operated bymeans of an electric motor 15 having a power shaft IS. A counter-shaft H is arranged opposite the motor shaft IS, the two shafts being connected to-' gether by means of a suitable gear reduction of any desirable construction arranged in gear casing l8. Onto the counter-shaft I! there is fixed a disk I9 which in the outer face thereof is provided with a radial slot 20, and this slot is a well known undercut type to hold and confine an adjustable wrist-pin 2! on which is hung one end of pitman 22. The other end of the pitman is connected by means of a pivot pin 23 with one of the arms of acentrally pivoted lever 24 which is loose upon the main stoker shaft 25. As shown more clearly in Fig. 8, the centrally pivoted lever 24 is held on the shaft 25 by means of a sleeve 26 fittedover the shaft and fixed thereto by means of. a'set-screw 2 or other suitable means.

Referring to Figs. 1, 2 and 4, fuel or coal hop per 28 is suitably supported as upon a two-part casing 29 which in turn is suported upon a suitable bottom frame or base 30, which also preferably supports the motor i5 and concomitant parts.

There is a primary coal well 3 l, as shown in Fig. 2, formed as an intermediate member of the twopart casing 29, which well is located directly below the bottom of the hopper 28. The bottom of the well is closed, and extending into and through one side of the well 3| there is a hori-' zontal screw conveyor 32 having a shaft 33, the conveyor extending horizontally and being located in a stationary pipe or conduit 34, which is supported at one end by the casing 29, to extend rearwardly away from the well 3 I. The adjacent end of the conveyor shaft 33 is inserted into a socket 35 of the main stoker shaft 25 extending away from the other side of the well 3|. Shaft 33 is rigidly fixed in the socket 35 as by a key or some other suitable means. An overbalanced dog 36 is pivoted on the other arm of the centrally pivoted lever 24, the tooth of the pawl being con stantly urged to engage with the teeth of. a ratchet wheel 31 which is mounted loosely upon the main stoker shaft 25 to drive the same as will hereinafter be more fully described.

Referring more particularly to Figs. 2, 5 and 6,

the fire pct 38 is preferably made of heavy cast iron and corrugated more or less as indicated by the shade lines which extend from top to bottom of the pot. If desired, the fire pot 38 may be provided as illustrated in Fig. 7 with integral tooth-like projections 39 which extend inwardly into thepot. The referred to corrugations either with or without the inward projections 39 will agitate the fuel or coal which is contained in the pct 38 for the purpose of conditioning it for more perfect burning when it is pushed upwardly into the bed of burning fuel. The necessary parts of the furnace including a grate, etc., with which the improved stoker may be used, do not need to be illustrated, as the use of the improved stoker will be clear to those skilled in the art.

A secondary fuel well 40 is located at the discharge end of the fuel conduit 34, such well being located below the pot 38. The coal is pushed upwardly by the conveyor 32 into the secondary well 40 for delivery into the pot 38. An annular casing 4| surrounds the fire pct 38, said casing preferably having an upward flare of less degree than the flare of the pot 38, the latter and the pot casing 4| being preferably offrusto-conlcal shape. .The pot casing 4| is supported upon and rigidly attached to a lower casing 42 which fl'ares more or less upwardly from its bottom and which casing is supported in stationary position in any suitable manner. The lower casing 42 encloses the secondary well 48. The fire pot 38 is provided at the top with an annular flange 43 which is located over the upper edge of the pot casing 4| and extends a suitable distance there beyond. The pot 38 rests upon ball bearings 44 which are located in a suitable race-way at the upper end of the secondary well 40, and these bearings preferably so support the pot as to space the annular flange 43 thereof a slight distance away from the ratchet teeth a gravity pawl 41 is provided which is pivoted to the upper end of a lever-arm 48 which in turn is pivoted at its lower end on pivot pin 49 formed on supporting bracket 50, which is rigidly mounted on the lower end of casing 42 and extends rearwardly therefrom. The lever 48 therefore extends upwardly from a point at the lower end of the casing 42 to a point adjacent the ratchet ring 45 so as to arrange the tooth of the pawl 41 in proper position for engaging the teeth 46 in succession and to thereby impart a step by step rotating movement to the fire pot 38. For limiting the movement of the lower end of the pawl 41 and to positively position the pawl in one direction, a stop 5| extends outwardly from the lever 48, the pawl being free to move in opposite direction and to slide over the ratchet teeth in succession.

Lever 48 is formed with elbow or crook 52 so as to enable the lever to extend upwardly more or less in a vertical position, and still enable the lever to do its intended work. Opposite the inner surface of the elbow 52 tappets 53, 54 are located, such tappets being formed from a single piece which is rigidly fixed to the rear end of the conveyor shaft 33. These parts are located entirely outside of the path of movement of the coal so as not to be interfered with thereby. An anti-friction roller 55 is mounted on the lever 48 at the elbow 52 for engagement by said tappets 53, 54. These tappets successively acting upon thev oscillatory lever 48 cause the fire pot 38 to be given a step by step motion at the same time that the coal is moving upwardly into the fire pot. The tappets are adapted to positively move the lever 48 in one direction, while in the other direction the lever is returned under the influence of spring tension. For this purpose a helical spring 56 is wound around the bracket 58, one arm 51 of such spring being hooked and engaged with the lever at that edge opposite to the tappets, while the other arm 58 of the spring bears firmly upon a stationary neck 59 extending from the lower casing 42, through which neck the adjacent end of conveyor shaft 33 passes.

Referring now to Figs. 8 and 9 in particular, the ratchet wheel 31 which delivers power from the pitman 22 to the main stoker shaft 25, is provided with an enlarged hub or annular flange 68 which extends rearwardly around the shaft 25. As before mentioned, the power ratchet 31 is mounted so that it may turn loosely upon shaft 25. A split clutch ring 8| is mounted upon the hub or flange 88 for frictional bearing relation therewith, the ring being adapted to be tightened. up by means of its bolt 62. A disk 83 is rigidly secured to the shaft 25 by a key 84, and said disk is provided with a stud 65 which enters a hole extending transversely of the clutch ring 6|, which latter is positioned between the outer edge portions of disk 63 and the ratchet wheel 31. It will be clear that if the shaft 25 and hence the conveyor 82 should not be rotated as freely as desirable, as by some obstruction or clogging of the coal, that the relative slip'between the disk 83 and the ratchet wheel 31 will act to prevent any injury to the power parts including the ratchet wheel 31 which might otherwise occur, and which slip will take place until the obstruction has been removed.

There is provided a slide member 66 extending radially of the shaft 26 and having an inclined or beveled surface 61 at its inner end, facing outwardly. This member 66 is adapted to slide in a radial slot 68 formed in the shaft 25, the

slide member 66 being confined to a definite outward movement by means of an annular retaining portion or flange 69 which is formed on the ratchet wheel 31 concentrically with, and within, the hub or flange 60. Said retaining flange 69 serves the double purpose of retaining the slide member 66 and as the space inside the flange 69 is eccentric to the axis of the shaft 25, it forms at its inner surface a cam 10 as shown more clearly in Fig. 9.

A slide rod ll is arranged in an axial bore 12 of the shaft 25, the inner end of which rod is in bearing relation with the inclined surface Bl of the slide member as clearly shown in Fig. 8. Towards its outer end the slide rod H is provided with a collar l3 which is located in an enlargement of the bore l2, such enlargement providing a shoulder '84 for the inward abutment of the collar 13. A helical expansion spring i5 is coiled around the slide rod ll, one endof the spring being seated against the collar l3 and the other end of the spring being confined by means of a perforated screw plug 78 which is screwed into the screw threaded outer end of the shaft 25.

The forward end ll of the rod 7! projects for a suitable distance beyond the shaft 25, at a point adjacent contact members lb, i9 included in the circuit of the electric motor 35 in a manner well known to those skilled in the art. The contact member it is stationary and the member 719 is movable and is provided with an insulator extension 8b which is arranged in cooperative relation with the projecting end ii of the slide rod. It is obvious herefrom that should clogging or obstruction occur in the feed of the coal through the conduit 35 or the concomitant parts to the rear, that the power will be automatically shut off because the loose ratchet wheel 3? will be given a turning movement upon the shaft 25 with the result that the cam it will act upon the slide member bit to cause it to press the slide rod ii outwardly and to thereby compress the spring '85 and bring the rods projecting end ii into bearing relation with the insulated part of the movable contact member '85-], and thereby push the contacts of the members it, '89 apart, thereby breaking the circuit. As soon as this is noted immediate steps may be taken to remove the obstruction or cause of clogging, and after removal the proper feed of the coal may be resumed. When it is resumed, the ratchet wheel 3? has been moved back to its original position, and the spring has acted upon the slide rod it so as to push the slide member 66 as far back as the retaining fiangefib will allow. This means that the projecting end ll of the slide rod has been moved rearwardly out of contact with the insulating portion 86 of the movable contact member it.

Preferably, auxiliary to the coal feeding means to the fire pot, there is provided means forcarrying away the ashes, etc. discharged from the furnace and whatever dust, etc. may fall from the stoker. To this end a sprocket wheel 8! keyed to the shaft 25 is secured by a pin or stud 82 directly to the disk 63 (Fig.3). As shown more clearly in Figs. 2 and 4, the sprocket chain 63 is driven from sprocket 8i and passes over a sprocket wheel M which is firmly fixed to the shaft 85 of a horizontal conveyor 86.. At its forward end the shaft 85 turns in suitable bearings of the frame or support 30. At its other end shaft 85 is supported in a bearing of a horizontal trough Bl which is suitably supported and which is provided at each side of the conveyor 86 with diverging ash catching plates or members 88, 89 (shown also in Fig. 5). A tube or pipe 90 connects the ash trough 81 with an ash well 9| which is located adjacent to the frame or support 30. outwardly and upwardly from the ash well 9! there extends a discharge chute 92 for the ashes. Within chute 92 there is a bucket conveyor 93 which is operated from a sprocket-wheel 94 fixed on the conveyor shaft 85.

It will be seen that although the shafts 33 and 85 revolve in the same direction, the conveyor 32 feeds the coal in one direction to the fire pot 38 and the conveyor 86 feeds the ashes in opposite direction, that is, in a direction away from the parts of the stoker which are above it. This is because the screw blades of the respective conveyors are the reverse the one to the other. Ashes, etc. dropping from the furnace or grate above the stoker are conducted by the inclined plates 88, 89 into the ash trough bl, from whence they are fed by the conveyor 86 into the ash well 95 from which they are discharged by the action of the bucket conveyor 93 to a suitable point of delivery. On reference to Figs. 2, 3 and 6 there will be seen a rotary perforated damper or valvelike disk 95 which is supported upon a perforated damper plate 96 which is rigidly secured to the extreme lower end of the lower casing Q2 of the stoker, at a point directly above the ash conveyor 86. an axial pivot 97 mounted in a bearing in the fixed plate 9b, a crank arm 98 (shown clearly in broken lines in Fig. 3) extending laterally from the pivot ill. With the outer end of the crank arm 98 there is connected the inner end of an actuating rod 99 which is of sufficient length to extend forwardly beyond the supporting frame 3@ to be conveniently accessible by an operator of the stoker. This rod Q9 may be operated from time to time as desired for the purpose of operating the shut-off or damper plate 95 so as to permit to drop into the trough 8? any dust or other particles which may have collected in the lower part of the casing 62 below the fire pot 38. If hand operation will not be desired, simple means may be installed for the automatic operation of the actuating rod 89.

Means are provided for conductingair to the fire pct 38. To this end, as shown more clearly in Figs. 1, 2 and 4 a tubular air conduit tilt surrounds the coal conveyor pipe 3 3. The air conduit ltd is sufiiciently larger than the pipe 36 so'that it will provide an ample air passage surrounding pipe it. A blower mi is operated by the shaft of the motor i5 and is connected by means of a pipe it? with the tubular air conduit W6, so that air may be blown into the space directly surrounding the coal feed pipe 36. An annular opening tilt in the casing d2 connects the space, through which the air is conducted, with an annular air chamber ltd which is located between the fire pot 38 and its surrounding casing it. This air chamber 0% communicates through perforations 38a in the iire pot with the interior thereof, so that air will be supplied in jets to the mass of coal contained in the pot, thereby to condition the coal for better, burning and to eliminate therein ingredients such as dust or the like which is eliminated from the fire pot 38 when the air supply is not working and may be allowed to gravitate downwardly through the perforations 38a, the air chamber I04, and into a chamber M5 in the lower part of the casing 42. Such dust and other particles are retained by the closed The perforated rotary plate 95 has damper plate 95 and are removed when the said damper plate is opened.

It should be stressed that the fire pot 38 being corrugated from top to bottom and also being provided with inward stirrer projections such as the projections 39, is adapted to considerably agitate the fuel in the pot and condition the fuel for more proper combustion, which features and concomitant features tend to produce more perfect combustion without the formation of clinkers. The corrugations furthermore allow for the expansion and contraction of the fire pot and prevent the cracking thereof under the influence of the heat.

It is obvious that the invention as shown and described is susceptible to a wide range of modification which may be resorted to by those skilled in the art without departing from the spirit of the invention as defined in the scope of the appended claims.

What I claim as new and of my invention and desire to secure by Letters Patent is,

1. In a stoker, the combination of a rotary fire pot, a screw conveyor for feeding fuel upwardly to the pot, an annular series of ratchet teeth on the rim of the pot, an upwardly extending lever pivoted at one side of the pot and provided with a pawl for successively engaging the teeth, and

a tappet on the conveyor shaft'for acting on the lever, whereby intermittent rotation is imparted to the pot.

2. In a stoker, the combination of a rotary fire pot having a rim, means for feeding fuel upwardly into the pot, and means including a pawl and ratchet device between the rim and such feeding means for rotating the pot with a step by step movement, the rim having the ratchet teeth.

3. In a stoker, the combination of a rotary fire pot having a rim, a screwconveyor for feeding fuel upwardly to the pot, an annular series of ratchet teeth on the underside of the rim of the pot, an upwardly extending lever pivoted at one side of and below the pot and provided with a pawl at its upper end for successively engaging the teeth, and oppositely extending tappets on the conveyor shaft for acting on the lever.

4. In astoker, the combination of a rotary fire pot provided with numerous perforations, and with inner, substantially vertical corrugations and tooth-like intermediate stirrer projections, means for feeding fuel upwardly into the pot, and means for conducting a .supply of air around the pot so as to issue from the perforations and pass into the pot.

SAMUEL G. BUSKARD. 

